When I was reading on Wiktionary, I found something interesting. The word for circle was traced back to a Greek word which was said to be "of Pre-Greek origin". However, I read about the word carcer, and found this:
From Proto-Italic *karkros, from Proto-Indo-European *kr-kr- (“circular”), reduplication of *(s)ker- (“to turn, bend”) in the sense of "enclosure".
This shows that, considering the fact that both words have "cr" in them and the letter c repeated twice, doesn't that mean that the word was (maybe or probably) from Proto-Indo-European which was inherited to Greek, Latin, Old French, and then English?
Note: this is bold because the normal * won't work.